Excerpts from netbsd: 21-Apr-98 USB device exploration Lennart
Augustsson@cs.ch (1009*)

> 1) Make an exploration pass during normal device probe
>    and attachment.  I dislike this because it would mean
>   operating the USB controller without the interrupts
>   on, and that would be painful.

I think there is no way around a polling mode. The keyboard
should work for DDB too, even if booted directly into the
debugger ("boot -d").
(Except DDB uses the emulation mode, which could
become ugly.)

best regards
Matthias